The present invention relates generally to test equipment for electronic devices. More particularly, the present invention relates to a temperature control device for maintaining constant operating temperature of an electronic device under test.
Electronic devices, such as integrated circuit chips, are usually tested prior to use. Device manufacturers typically perform a number of electrical and physical tests to ensure that the devices are free from defects and that the devices function according to their specifications. Common types of device testing include burn-in testing and electrical performance testing.
The operating temperature of an electronic device under test (DUT) is an important test parameter that usually requires careful monitoring and/or regulating. For example, an electrical test procedure may designate a number of specific test temperatures or a specific range of test temperatures. Consequently, the prior art is replete with different types of temperature control systems, heat sink components, and heater elements designed to heat, cool, and otherwise control the operating temperature of a DUT. These temperature control systems are designed to maintain a steady state DUT operating temperature during the electronic testing procedure. However, it can be difficult to regulate the temperature of a DUT if the DUT exhibits rapid or excessive internal temperature changes while being tested; the electronic devices within the DUT often generate heat which causes such internal temperature changes.
Active thermal control (ATC) systems measure, derive, or estimate the real-time temperature of a DUT while it is being tested and utilize the real-time DUT temperature to control the operations of ATC system components. Most ATC systems employ a cooling component such as a heat sink, a fan element, a radiator, or the like, and a heater. Thus, if the temperature of the DUT exceeds the specified test temperature, then the temperature of the heater within the heater/heat sink unit can be reduced and/or the operation of the cooling component can be adjusted to increase its effect. If the temperature of the DUT is less than the specified test temperature, then the temperature of the heater can be increased and/or the operation of the cooling component can be adjusted to decrease its effect. Some prior art ATC systems utilize a heat sink layer covered by a heater element. In this configuration, excess heat from a DUT must pass through the heater element or layer before it reaches the heat sink. Consequently, this prior art configuration may not be capable of efficiently and effectively compensating for rapid temperature fluctuations generated by the DUT.
A preferred embodiment of the present invention is realized as a combined heater and heat sink assembly. The assembly can be used in an active thermal control system that regulates the temperature of an electronic device under test (DUT). The assembly is suitably configured to reduce the thermal resistance between the DUT and a thermal cold source or heat sink, while concurrently reducing the thermal resistance between the DUT and a thermal hot source or heater. In other words, the assembly is configured such that the DUT is concurrently exposed to relatively hot and cold sources. This allows faster thermal response time such that the control system can quickly add heat to or remove heat from the DUT in response to fluctuations in the test temperature of the DUT.
The above and other aspects of the present invention may be carried out in one form by a temperature control apparatus that includes a heater assembly configured to directly heat a DUT and a heat sink configured to provide a direct thermal path between the DUT and a cold source.